1The action of uniting two or more things, or of uniting one thing with another; the fact or condition of being united; union.
2In Christian contexts: the action of uniting the human with the divine; the result of this. Frequently with to, with.
Sometimes distinguished from union.
Late Middle English; earliest use found in Guy de Chauliac's Grande Chirurgie. From post-classical Latin unition-, unitio union from classical Latin ūnīt-, past participial stem of ūnīre + -iō.